Photographing with Higher MP bodies

Started 3 months ago | Discussions thread
beatboxa Veteran Member • Posts: 7,480
Re: Photographing with Higher MP bodies

djd97 wrote:

beatboxa wrote:

ShutterDude wrote:

While I wait for the Z7ii release, it'll give me some time to debate whether I should invest in that body vs the Z6ii - the main driver is the ability to crop if I need to given the higher MP count, and wanting to print larger prints as well.

Other than that, it was mentioned that using a higher megapixel body will be more sensitive to motion resulting in softer images, and as well the requirement for top notch optics. In other words, it's less forgiving that using a lower MP camera.

Can anyone chime more on this?


I would say: forget about MP for a minute. Think instead about enlargement.

When you enlarge more, what do you do? You will:

  • increase the apparent lens aberrations ("less sharp")
  • decrease the apparent DoF
  • increase the apparent noise
  • increase the apparent pixellation (this is the resolution / MP part)
  • decrease the frame's angle of view
  • decrease the apparent dynamic range
  • increase the apparent posterization / decrease tonality
  • increase the apparent motion blur

All of that comes from more enlargement, with only one of then coming from pixel density. Causation rather than correlation is important here. It's the same thing that happens when you pixel peep or zoom in more to an image.

So you should ask yourself what the bottleneck is: Is it pixelation, or any of the others above?

With all that said, you can largely predict the results fairly accurately. For example, if you enlarged more by a factor of 1.4x, you would magnify the 1D/linear issues by 1.4x and the 2D issues by 2x. So motion blur would become 1.4x as large, while DR would decrease by around 1 stop, for example.

Why would the DR appear to be effected from a simple crop? Isn't DR tied to pixel size/quality (which shouldn't change from cropping)?

No, DR is not tied to pixel size / quality. In fact, a single pixel in any image (regardless of size or quality of that pixel) has 0 stops of DR because it has only a single "distinguishable" value.

DR--and in this case, what I called "apparent DR" is more tied to the ratios of saturation and noise, or the highest values where one can no longer distinguish between tones and the lowest values. As one enlarges more (and crops), the same amount of light is spread over a larger area, decreasing these ratios. It's just like when you move a movie projector further back from a screen--eventually, the "image" will have 0 contrast.

This is why crop areas always have lower DR, typically proportional to areas.

For example:

BTW, it's also the reason you see blurbs like this on those sites:

  • "If, in order to get sufficient IQ, you are printing smaller or viewing further away than you would like; then start by determining the highest ISO that gives reasonable IQ for an 8" wide print viewed at arms length.Then take this PDR value and increase it to meet your needs. Remember, one stop of PDR is a 2 improvement in linear size or viewing distance."
  • "It is important to understand that the print size and viewing distance, the Circle Of Confusion (COC), determines not only the target PDR, but the PDR above which you may not see any visible difference.In other words, one camera may be better than another at a particular ISO, but the difference may not be visible given your viewing conditions."
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